function calculate() {
  let g = 9.8
  // let input1 = parseFloat(document.getElementById("input1").value);   //r
  let input2 = parseFloat(document.getElementById("input2").value);   //d
  let input3 = parseFloat(document.getElementById("input3").value);  //h
  let input4 = parseFloat(document.getElementById("input4").value);   //L
  let input5 = parseFloat(document.getElementById("input5").value);  //C


  // if (!input1 ) input1  = 0;
  if (!input2 ) input2  = 0;
  if (!input3 ) input3  = 0;  
  if (!input4 ) input4  = 0;
  if (!input5 ) input5  = 0;  


  // v的结果
  let r = input5*input5 / 8 * input4 + input4 / 2

  let result = Math.sqrt(g*r*input2/2*input3) * 3.6;


  if (result == 'NaN') {
    result = 0
    alert('请按要求输入数据！')
    location.reload()
  }

  document.getElementById("result").textContent = result.toFixed(2);
}